U.S. patent number 10,903,950 [Application Number 16/485,209] was granted by the patent office on 2021-01-26 for method and apparatus for transmitting uplink transport block in wireless communication system.
This patent grant is currently assigned to LG Electronics Inc.. The grantee listed for this patent is LG Electronics Inc.. Invention is credited to Joonkui Ahn, Ilmu Byun, Bonghoe Kim, Yunjung Yi, Sukhyon Yoon.
View All Diagrams
United States Patent |
10,903,950 |
Kim , et al. |
January 26, 2021 |
Method and apparatus for transmitting uplink transport block in
wireless communication system
Abstract
A method and device for transmitting a transport block in a
wireless communication system is provided. Particularly, a terminal
receives, from a base station, information on the number of
subcarriers in a partial band included in an allocated carrier. The
terminal distributes a soft buffer possessed by the terminal in
proportion to the number of subcarriers in the partial band. The
terminal determines a transport block size for each partial band
according to the size of the distributed soft buffer. The terminal
transmits, to the base station, the transport block within the
transport block size.
Inventors: |
Kim; Bonghoe (Seoul,
KR), Byun; Ilmu (Seoul, KR), Ahn;
Joonkui (Seoul, KR), Yoon; Sukhyon (Seoul,
KR), Yi; Yunjung (Seoul, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG Electronics Inc. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG Electronics Inc. (Seoul,
KR)
|
Appl.
No.: |
16/485,209 |
Filed: |
March 16, 2018 |
PCT
Filed: |
March 16, 2018 |
PCT No.: |
PCT/KR2018/003076 |
371(c)(1),(2),(4) Date: |
August 12, 2019 |
PCT
Pub. No.: |
WO2018/174473 |
PCT
Pub. Date: |
September 27, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190394000 A1 |
Dec 26, 2019 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
62473475 |
Mar 19, 2017 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
5/0046 (20130101); H04L 5/0007 (20130101); H04L
5/0094 (20130101) |
Current International
Class: |
H04L
5/00 (20060101) |
Field of
Search: |
;370/330 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International Search Report of Appl'n No. PCT/KR2018/003076, dated
Jun. 18, 2018. cited by applicant .
Huawei et al., "On DL Multiplexing of URLLC and eMBB
Transmissions," R1-1701663, 3GPP TSG RAN WG1 Meeting #88, Athens,
Greece, Feb. 7, 2017, see section 2; and figure 1. cited by
applicant .
NEC, "Numerology Indication for a Mixed Numerology Carrier,"
R1-1701979, 3GPP TSG RAN WG1 Meeting #88, Athens, Greece, Feb. 6,
2017, see sections 1, 2.1; and figure 2. cited by
applicant.
|
Primary Examiner: Solinsky; Peter G
Attorney, Agent or Firm: Dentons US LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the National Stage filing under 35 U.S.C. 371
of International Application No. PCT/KR2018/003076, filed on Mar.
16, 2018, which claims the benefit of U.S. Provisional Application
No. 62/473,475 filed on Mar. 19, 2017, the contents of which are
all hereby incorporated by reference herein in their entirety.
Claims
What is claimed is:
1. A method for transmitting a transport block in a wireless
communication system, comprising: receiving, by a user equipment
(UE), information on a number of subcarriers of a partial band
being included in a carrier that is allocated by a base station;
distributing, by the UE, a soft buffer belonging to the UE in
proportion to a number of subcarriers of the partial band;
determining, by the UE, a transport block size per partial band
based on a size of the distributed soft buffer; and transmitting a
transport block, to the base station, within the transport block
size.
2. The method of claim 1, wherein, if a bandwidth of the partial
band is constant and a gap between the subcarriers is increased, a
number of subcarriers of the partial band is decreased, a size of
the soft buffer being distributed to the partial band is decreased,
and a transport block size being transmitted from the partial band
is decreased.
3. The method of claim 1, wherein, if a bandwidth of the partial
band is increased and a gap between the subcarriers is constant, a
number of subcarriers of the partial band is increased, a size of
the soft buffer being distributed to the partial band is increased,
and a transport block size being transmitted from the partial band
is increased.
4. The method of claim 1, wherein, in case the partial band
includes a first partial band and a second partial band, a sum of a
bandwidth of the first partial band and a bandwidth of the second
partial band is equal to or greater than a bandwidth of the
carrier.
5. The method of claim 1, wherein, in case the partial band
includes a first partial band and a second partial band, a sum of a
number of subcarriers in the first partial band and a number of
subcarriers in the second partial band is equal to or greater than
a number of subcarriers in the carrier.
6. The method of claim 5, wherein the first partial band supports
enhanced Mobile BroadBand (eMBB) services, and wherein the second
partial band supports Ultra-Reliable and Low Latency Communications
(URLLC).
7. The method of claim 1, wherein the soft buffer belonging to the
UE is distributed in proportion to a number of Orthogonal Frequency
Division Multiplexing (OFDM) symbols being scheduled in the partial
band, and wherein the number of OFDM symbols being scheduled in the
partial band is received via higher layer signal.
8. The method of claim 1, wherein the soft buffer belonging to the
UE is distributed in proportion to a number of Hybrid Automatic
Repeat request (HARQ) processes of the partial band, and wherein
the number of HARQ processes is received via UE-specific
signal.
9. The method of claim 1, wherein the soft buffer belonging to the
UE is distributed in proportion to a maximum number of information
bits being supported by a maximum modulation scheme of the partial
band.
10. The method of claim 1, wherein the soft buffer belonging to the
UE is distributed in inverse proportion to a minimum coding rate
being applied to the partial band, and wherein the minimum coding
rate is received via UE-specific signal.
11. The method of claim 1, wherein, in case multiple carriers are
allocated from the base station, the soft buffer belonging to the
UE is distributed in proportion to a number of subcarriers of the
carrier, before the soft buffer is distributed in proportion to a
number of subcarriers of the partial band.
12. The method of claim 1, wherein the UE is simultaneously
connected to a first communication system and a second
communication system, wherein, based on a number of cells being
configured to the first communication system and a number of cells
being configured to the second communication system, the soft
buffer belonging to the UE is distributed to each of the first
communication system and the second communication system, wherein
the number of cells being configured to the first communication
system is acquired based on a bandwidth being supported by the
first communication system, and wherein the number of cells being
configured to the second communication system is acquired based on
a bandwidth being supported by the second communication system.
13. A user equipment transmitting a transport block in a wireless
communication system, comprising: a transceiver transmitting or
receiving radio signals; and a processor controlling the
transceiver, wherein the processor: receives information on a
number of subcarriers of a partial band being included in a carrier
that is allocated by a base station, distributes a soft buffer
belonging to the UE in proportion to a number of subcarriers of the
partial band, determines a transport block size per partial band
based on a size of the distributed soft buffer, and transmits a
transport block, to the base station, within the transport block
size.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
This specification relates to wireless communication and, most
particularly, to a method for transmitting an uplink transport
block in a wireless communication system and an apparatus (or
device) using the same.
Related Art
A wireless communication system is widely deployed to provide
various types of communication services, such as voice and data. An
object of a wireless communication system is to enable a plurality
of terminals to perform reliable communication regardless of their
locations and mobility.
A requirement of a next-generation wireless communication system is
to accommodate significantly explosive data traffic, to increase a
dramatic increase in a transfer rate per user, to accommodate the
significantly increased number of connected devices, and to support
a very low end-to-end (E2E) latency and high energy efficiency. For
this, there is ongoing research on various techniques such as dual
connectivity, massive multiple input multiple output (MIMO),
in-band full duplex, non-orthogonal multiple access (NOMA), super
wideband support, device networking, or the like.
A base station (BS) properly allocates radio resources to each
piece of user equipment (UE) within a cell through scheduling. The
UE may transmit control information or user data to the BS using
the allocated radio resources. In this case, a method for
transmitting control information and a method for transmitting user
data may be different. Furthermore, a method for allocating radio
resources for control information and a method for allocating radio
resources for user data may be different. Accordingly, radio
resources for control information and radio resources for user data
may be different. A BS may differently manage radio resources
reserved for control information and radio resources reserved for
user data.
In a mobile communication system, data is transmitted/received
through a resource allocation process based on BS scheduling to
maximize resource utilization, which may lead to an increase in
latency of uplink data transmission of a UE. Accordingly, a method
of performing a multi-level scheduling request is proposed to
minimize the latency of the UE.
SUMMARY OF THE INVENTION
Technical Objects
This specification provides a method and apparatus for transmitting
an uplink transport block in a wireless communication system.
Technical Solutions
This specification proposes a method and apparatus (or device) for
transmitting an uplink transport block in a wireless communication
system.
The device (or apparatus) includes a transceiver transmitting and
receiving radio signals and a processor being operatively connected
to the transceiver.
This exemplary embodiment proposes a method of efficiently
splitting (or dividing), by a UE being connected to multiple
partial bands or carriers, a soft buffer for carriers and partial
bands. The UE may be allocated with at least one carrier, and the
specific carrier may include at least one partial band. If the
number of partial bands is equal to 1, it may be understood that
the specific carrier is not split (or divided) to partial
bands.
The UE receives information on the number of subcarriers in a
partial band being included in the allocated carrier from the base
station. The number of subcarriers in the partial band may be
explicitly or implicitly received from the base station via higher
layer signaling.
The UE may distribute a soft buffer included in the UE in
proportion to the number of subcarriers of the partial band. For
example, if the partial band includes a first partial band and a
second partial band, the soft buffer may be distributed based on
the number of subcarriers in the first partial band and the number
of subcarriers in the second partial band.
The UE determines a transport block size per partial band based on
the distributed soft buffer size. The transport block size may
correspond to a maximum transport block size that can be
transmitted from the partial band.
The UE transmits a transport block to the base station within the
determined transport block size.
If the bandwidth of the partial band is constant whereas a gap
between the subcarriers increases, the number of subcarriers of the
partial band may be decreased. Accordingly, the soft buffer size
being distributed to the partial band is decreased, and the
transport block size being transmitted from the partial band may be
decreased.
If the bandwidth of the partial band is increased whereas a gap
between the subcarriers is constant, the number of subcarriers of
the partial band may be increased. Accordingly, the soft buffer
size being distributed to the partial band is increased, and the
transport block size being transmitted from the partial band may be
increased.
In case the partial band includes a first partial band and a second
partial band, a sum (or combination) of a bandwidth of the first
partial band and a bandwidth of the second partial band may be
equal to or larger than the bandwidth of the carrier. In this case,
the first partial band and the second partial band may be processed
with Frequency Division Multiplexing (FDM).
In case the partial band includes a first partial band and a second
partial band, a sum (or combination) of a number of subcarriers in
the first partial band and a number of subcarriers in the second
partial band may be equal to or larger than the number of
subcarriers in the carrier. In this case, the first partial band
and the second partial band may overlap one another. For example,
the first partial band may support enhanced Mobile BroadBand (eMBB)
services, and the second partial band may support Ultra-Reliable
and Low Latency Communications (URLLC) services. More specifically,
the first partial band may correspond to a partial band dedicated
to eMBB services using only part of the entire band, and the second
partial band may correspond to a partial band dedicated to URLLC,
which may use the entire band. The entire band may correspond to
the entire carrier band being allocated to the UE.
Additionally, the soft buffer belonging to the UE may be
distributed in proportion to a number of Orthogonal Frequency
Division Multiplexing (OFDM) symbols being scheduled in the partial
band. More specifically, if a gap between the subcarriers and the
bandwidth are constant, the soft buffer size or maximum transport
block size may vary (or change) in proportion to the number of
symbols, which corresponds to units for performing scheduling of
the partial band. The number of OFDM symbols being scheduled in the
partial band may be received via higher layer signal.
Additionally, the soft buffer belonging to the UE may be
distributed in proportion to a number of Hybrid Automatic Repeat
request (HARQ) processes of the partial band. The number of HARQ
processes may be received via UE-specific signal.
Additionally, the soft buffer belonging to the UE may be
distributed in proportion to a maximum number of information bits
being supported by a maximum modulation scheme of the partial band.
For example, in case the maximum modulation scheme of the first
partial band is 1024QAM and the maximum modulation scheme of second
partial band is 256QAM, a maximum of 10-bit information may be
transmitted from 1 RE in the first partial band, and a maximum of
8-bit information may be transmitted from 1 RE in the second
partial band. Therefore, under the same condition, among the entire
soft buffer, 10/18 of the buffer is allocated to the first partial
band, and 8/18 of the buffer is allocated to the second partial
band.
Additionally, the soft buffer belonging to the UE may be
distributed in inverse proportion to a minimum coding rate being
applied to the partial band. The minimum coding rate may be
received via UE-specific signal. Furthermore, the UE may distribute
the soft buffer based on the minimum coding rate as well as the
maximum coding rate or the reference coding rate.
In case multiple carrier are allocated from the base station, the
soft buffer belonging to the UE may be distributed in proportion to
the number of subcarriers of the carrier before the soft buffer is
distributed in proportion to the number of subcarriers of the
partial band. More specifically, after the UE distributes its soft
buffer to each carrier, the UE may re-distribute the soft buffer
per partial band.
The UE may be simultaneously connected to a first communication
system and a second communication system. The first communication
system may correspond to a 5G NR system, and the second
communication system may correspond to an LTE system. Based on a
number of cells being configured to the first communication system
and a number of cells being configured to the second communication
system, the soft buffer belonging to the UE may be distributed to
each of the first communication system and the second communication
system.
At this point, the number of cells being configured to the first
communication system may be acquired based on a bandwidth that is
supported by the first communication system. And, the number of
cells being configured to the second communication system may be
acquired based on a bandwidth that is supported by the second
communication system. Since the 5G NR system supports a wider
bandwidth than the LTE system, the number of cells being configured
to the first communication system may be greater than the number of
cells being configured to the second communication system.
Effects of the Invention
When using the proposed method, by efficiently splitting a soft
buffer, which is reserved by a user equipment (UE), to each carrier
and partial band, a transmission rate of the UE may be increased or
a size of a soft buffer that shall be reserved by the UE may be
reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a wireless communication system to which the present
invention is applied.
FIG. 2 is a diagram illustrating a radio protocol architecture for
a user plane.
FIG. 3 is a diagram illustrating a radio protocol architecture for
a control plane.
FIG. 4 is a drawing for explaining a method of dynamically
assigning a radio resource.
FIG. 5 is a drawing for explaining an SPS method.
FIG. 6 is a diagram showing a procedure for transmitting a
transport block according to an exemplary embodiment of this
specification.
FIG. 7 is a block diagram showing a wireless device to which an
exemplary embodiment of this specification can be applied.
FIG. 8 is a block diagram showing an example of a device being
included in a processor.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
The technology described below can be used in various wireless
communication systems such as code division multiple access (CDMA),
frequency division multiple access (FDMA), time division multiple
access (TDMA), orthogonal frequency division multiple access
(OFDMA), single carrier frequency division multiple access
(SC-FDMA), etc. The CDMA can be implemented with a radio technology
such as universal terrestrial radio access (UTRA) or CDMA-2000. The
TDMA can be implemented with a radio technology such as global
system for mobile communications (GSM)/general packet ratio service
(GPRS)/enhanced data rate for GSM evolution (EDGE). The OFDMA can
be implemented with a radio technology such as institute of
electrical and electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE
802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), etc. The UTRA
is a part of a universal mobile telecommunication system (UMTS).
3rd generation partnership project (3GPP) long term evolution (LTE)
is a part of an evolved UMTS (E-UMTS) using the E-UTRA. The 3GPP
LTE uses the OFDMA in a downlink and uses the SC-FDMA in an
uplink.
For clarity of explanation, the following description will focus on
the 3GPP LTE/LTE-A. However, technical features of the present
invention are not limited thereto.
FIG. 1 shows a wireless communication system to which the present
invention is applied. The wireless communication system may also be
referred to as an evolved-UMTS terrestrial radio access network
(E-UTRAN) or a long term evolution (LTE)/LTE-A system.
The E-UTRAN includes at least one base station (BS) (20) which
provides a control plane and a user plane to a user equipment (UE)
(10). The UE (10) may be fixed or mobile, and may be referred to as
another terminology, such as a mobile station (MS), a user terminal
(UT), a subscriber station (SS), a mobile terminal (MT), a wireless
device, etc. The BS (20) is generally a fixed station that
communicates with the UE (10) and may be referred to as another
terminology, such as an evolved node-B (eNB), a base transceiver
system (BTS), an access point, etc.
The BSs (20) are interconnected by means of an X2 interface. The
BSs (20) are also connected by means of an S1 interface to an
evolved packet core (EPC) (30), more specifically, to a mobility
management entity (MME) through S1-MME and to a serving gateway
(S-GW) through S1-U.
The EPC (30) includes an MME, an S-GW, and a packet data
network-gateway (P-GW). The MME has access information of the UE or
capability information of the UE, and such information is generally
used for mobility management of the UE. The S-GW is a gateway
having an E-UTRAN as an end point. The P-GW is a gateway having a
PDN as an end point.
A radio interface between the UE and the BS is called a Uu
interface. Layers of a radio interface protocol between the UE and
the network can be classified into a first layer (L1), a second
layer (L2), and a third layer (L3) based on the lower three layers
of the open system interconnection (OSI) model that is well-known
in the communication system. Among them, a physical (PHY) layer
belonging to the first layer provides an information transfer
service by using a physical channel, and a radio resource control
(RRC) layer belonging to the third layer serves to control a radio
resource between the UE and the network. For this, the RRC layer
exchanges an RRC message between the UE and the BS.
FIG. 2 is a diagram illustrating a radio protocol architecture for
a user plane. FIG. 3 is a diagram illustrating a radio protocol
architecture for a control plane. The user plane is a protocol
stack for user data transmission. The control plane is a protocol
stack for control signal transmission.
Referring to FIG. 2 and FIG. 3, a PHY layer provides an upper layer
with an information transfer service through a physical channel.
The PHY layer is connected to a medium access control (MAC) layer
which is an upper layer of the PHY layer through a transport
channel Data is transferred between the MAC layer and the PHY layer
through the transport channel. The transport channel is classified
according to how and with what characteristics data is transmitted
through a radio interface.
Between different PHY layers, i.e., a PHY layer of a transmitter
and a PHY layer of a receiver, data are transferred through the
physical channel. The physical channel is modulated using an
orthogonal frequency division multiplexing (OFDM) scheme, and
utilizes time and frequency as a radio resource.
A function of the MAC layer includes mapping between a logical
channel and a transport channel and multiplexing/de-multiplexing on
a transport block provided to a physical channel over a transport
channel of a MAC service data unit (SDU) belonging to the logical
channel. The MAC layer provides a service to a radio link control
(RLC) layer through the logical channel.
A function of the RLC layer includes RLC SDU concatenation,
segmentation, and reassembly. To ensure a variety of quality of
service (QoS) required by a radio bearer (RB), the RLC layer
provides three operation modes, i.e., a transparent mode (TM), an
unacknowledged mode (UM), and an acknowledged mode (AM). The AM RLC
provides error correction by using an automatic repeat request
(ARQ).
Functions of a packet data convergence protocol (PDCP) layer in the
user plane include user data delivery, header compression, and
ciphering. Functions of a PDCP layer in the control plane include
control-plane data delivery and ciphering/integrity protection.
A radio resource control (RRC) layer is defined only in the control
plane. The RRC layer serves to control the logical channel, the
transport channel, and the physical channel in association with
configuration, reconfiguration and release of radio bearers
(RBs).
An RB is a logical path provided by the first layer (i.e., the PHY
layer) and the second layer (i.e., the MAC layer, the RLC layer,
and the PDCP layer) for data delivery between the UE and the
network. The configuration of the RB implies a process for
specifying a radio protocol layer and channel properties to provide
a particular service and for determining respective detailed
parameters and operations. The RB can be classified into two types,
i.e., a signaling RB (SRB) and a data RB (DRB). The SRB is used as
a path for transmitting an RRC message in the control plane. The
DRB is used as a path for transmitting user data in the user
plane.
When an RRC connection is established between an RRC layer of the
UE and an RRC layer of the network, the UE is in an RRC connected
state, and otherwise the UE is in an RRC idle state.
Data is transmitted from the network to the UE through a downlink
transport channel. Examples of the downlink transport channel
include a broadcast channel (BCH) for transmitting system
information and a downlink-shared channel (SCH) for transmitting
user traffic or control messages. The user traffic of downlink
multicast or broadcast services or the control messages can be
transmitted on the downlink-SCH or an additional downlink multicast
channel (MCH). Data are transmitted from the UE to the network
through an uplink transport channel. Examples of the uplink
transport channel include a random access channel (RACH) for
transmitting an initial control message and an uplink SCH for
transmitting user traffic or control messages.
Examples of logical channels belonging to a higher channel of the
transport channel and mapped onto the transport channels include a
broadcast channel (BCCH), a paging control channel (PCCH), a common
control channel (CCCH), a multicast control channel (MCCH), a
multicast traffic channel (MTCH), etc.
Hereinafter, semi-persistent scheduling (SPS) is described.
In a next-generation communication system, the SPS is required for
a plurality of UEs. An Internet of Things (IoT) service of various
industries is expected to be introduced in the next-generation
communication system. Representative examples thereof include an
automobile, a drone, or the like. In these services, location
information is expected to be updated in unit of 100 millisecond
(ms) to 1 second (s) to manage autonomous driving and to prevent
accidents. When the location information is updated periodically,
the SPS is applied in general to decrease an overhead of an
unnecessary control channel.
FIG. 4 is a drawing for explaining a method of dynamically
assigning a radio resource. FIG. 5 is a drawing for explaining an
SPS method.
A typical process of transmitting data from a UE to an eNB (a
method of dynamically assigning a radio resource) is described
below with reference to FIG. 4. First, the UE may request the eNB
to provide a radio resource required for transmission of generated
data (S401). Therefore, the eNB may assign the radio resource
through a control signal according to a radio resource request of
the UE (S402). In an LTE system, the resource assignment of the eNB
for transmitting UL data of the UE may be transmitted through a UL
grant transmitted through a PDCCH. Therefore, the UE may transmit
data to the eNB through the assigned radio resource (S403). The
radio resource request of the UE, the resource assignment of the
eNB, and corresponding UL data transmission of the UE may be
optionally repeated (S408 to S410).
Meanwhile, when the eNB transmits downlink (DL) data to the UE, a
DL assignment message may be transmitted to the UE through the
PDCCH to know through which radio resource the data transmitted to
the UE is transmitted (S404), and the eNB may transmit data to the
UE through a radio resource corresponding to the DL assignment
message (S405). In this case, DL assignment information
transmission and DL data transmission through a radio resource
corresponding thereto may be achieved in the same transmission time
interval (TTI). Further, as shown in FIG. 4, the DL data
transmission procedure may be repeated.
A method of assigning an SPS radio resource is a method in which
first and second steps are skipped in three steps for transmitting
data to the eNB (i.e., (1) the resource request of the UE, (2) the
resource assignment of the eNB, and (3) the data transmission of
the UE according to the resource assignment). Accordingly, the UE
may perform a process of transmitting data directly without the
aforementioned first and second steps, i.e., the step of requesting
the radio resource and the step of assigning the radio resource, on
the basis of a configuration of the radio resource. The concept of
the SPS method is shown in FIG. 5. That is, in the SPS method, the
eNB does not have to transmit radio resource assignment information
all the time through the PDCCH.
Hereinafter, a Buffer Status Report (BSR) will be described.
A BSR corresponds to information being fed-back to the base station
by a user equipment (UE) considering (or based on) a transport data
size of the UE. Table 1 shown below represents an example for
setting up (or configuring) a buffer size level according to the
BSR.
TABLE-US-00001 TABLE 1 Buffer Size (BS) Index value [bytes] 0 .sup.
BS = 0 1 0 < BS <= 10 2 10 < BS <= 12 3 12 < BS
<= 14 4 14 < BS <= 17 5 17 < BS <= 19 6 19 < BS
<= 22 7 22 < BS <= 26 8 26 < BS <= 31 9 31 < BS
<= 36 10 36 < BS <= 42 11 42 < BS <= 49 12 49 <
BS <= 57 13 57 < BS <= 67 14 67 < BS <= 78 15 78
< BS <= 91 16 91 < BS <= 107 17 107 < BS <= 125
18 125 < BS <= 146 19 146 < BS <= 171 20 171 < BS
<= 200 21 200 < BS <= 234 22 234 < BS <= 274 23 274
< BS <= 321 24 321 < BS <= 376 25 376 < BS <= 440
26 440 < BS <= 515 27 515 < BS <= 603 28 603 < BS
<= 706 29 706 < BS <= 826 30 826 < BS <= 967 31 967
< BS <= 1132 32 1132 < BS <= 1326 33 1326 < BS <=
1552 34 1552 < BS <= 1817 35 1817 < BS <= 2127 36 2127
< BS <= 2490 37 2490 < BS <= 2915 38 2915 < BS <=
3413 39 3413 < BS <= 3995 40 3995 < BS <= 4677 41 4677
< BS <= 5476 42 5476 < BS <= 6411 43 6411 < BS <=
7505 44 7505 < BS <= 8787 45 8787 < BS <= 10287 46
10287 < BS <= 12043 47 12043 < BS <= 14099 48 14099
< BS <= 16507 49 16507 < BS <= 19325 50 19325 < BS
<= 22624 51 22624 < BS <= 26487 52 26487 < BS <=
31009 53 31009 < BS <= 36304 54 36304 < BS <= 42502 55
42502 < BS <= 49759 56 49759 < BS <= 58255 57 58255
< BS <= 68201 58 68201 < BS <= 79846 59 79846 < BS
<= 93479 60 93479 < BS <= 109439 61 109439 < BS <=
128125 62 128125 < BS <= 150000 63 .sup. BS > 150000
Referring to Table 1, the UE divides (or splits) an uplink data
size to 64 levels and transmits information on the uplink data size
by using a 6-bit BSR. For example, in case the size of the uplink
data that is to be transmitted by the UE is equal to 350 bytes, the
UE transmits index value 24 by using a 6-bit BSR.
In case of an uplink, the base station configures a memory of a
soft buffer based on the BSR information, which is received from
the UE. More specifically, since a soft buffer size per UE
corresponds to a region where the soft buffer value is stored prior
to a channel decoding process, the base station must know the BSR
information.
If the base station does not know the BSR information, the base
station shall configure (or set up) the size of the soft buffer by
assuming a size of the uplink data as the largest data size.
However, in case of configuring the soft buffer size by assuming
the largest data size, this method is disadvantageous in that it
may cause a waste in memory of the base station.
Similarly, in case the base station configures the soft buffer by
assuming a random data size, since the base station does not know
the size of the data that is to be transmitted from the UE,
eventually, this may lead to a problem in that data cannot be
written in the soft buffer (i.e., in case the uplink data is larger
than the size of the soft buffer). As a result, in case the base
station randomly configures the soft buffer, the base station may
be capable of performing channel decoding. However, this method is
disadvantageous in that loss in uplink data may occur.
Additionally, a 5G New RAT (NR) communication system provides
multiple numerology and multiple bandwidth. In a frequency of 6 GHz
or less, a minimum bandwidth of 5 MHz may be supported, and, in a
frequency of 6 GHz or higher, a maximum bandwidth of 400 MHz may be
supported. A subcarrier width may be supported starting from 15 kHz
to 30, 60, and 120 kHz, time units for scheduling include
subframes, slots, and mini-slots. Since the length of the
subframes, slots, and mini-slots is defined as the number of OFDM
symbols, if the subcarrier width increases the actual scheduling
time unit that is applied decreases.
The bandwidth, subcarrier width, scheduling unit, and so on, act as
the main parameters for determining a maximum transport block (TB)
within a single carrier in an NR communication system. Therefore, a
maximum TB size that can be transmitted by a UE or base station
(BS) in each carrier of the NR communication system may also be
assigned with diverse values. If the maximum TB size is large, it
is also preferable to increase the size of the soft buffer, which
stores the TB. Therefore, soft buffer sizes that are adequate (or
appropriate) for each carrier may also be assigned with diverse
values.
Additionally, a partial bandwidth may be adopted in the 5G NR
communication system. Also, different numerologies may be adopted
to a single carrier in the 5G NR communication system. The
different numerologies may be positioned according to an FDM scheme
or may be positioned according to a TDM scheme. Herein, although
partial bands having different numerologies are processed as the
same cell, since the numerologies are different from one another, a
partial band reserves a separate retransmission process. Therefore,
a UE receiving a signal from different partial bands shall
configure a soft buffer size in order to be capable of processing a
retransmission process of each partial band.
Additionally, in the 5G NR communication system, the buffer needs
to be unevenly (or unequally) split (or divided). A case where a
soft buffer size enabling the UE to receive a transmission rate of
X Gbps is equal to Z will be assumed. In case the UE receives a
signal from 2 carriers, if the buffer is equally (or evenly) split
(i.e., equal buffer splitting), the soft buffer size being applied
to each carrier is equal to Z/2, and, accordingly, the maximum TB
size that can be received from each carrier is reduced to 1/2.
Therefore, the maximum transmission rate that can be received in
each carrier is also equal to X/2 Gbps.
In LTE, the maximum bandwidth of a single carrier was merely 20
MHz. However, in NR, since the maximum bandwidth increases to a
maximum of 400 MHz, problems caused by equally dividing (or
splitting) the buffer may increase even more. A case where the
bandwidth of Carrier 1, through which the UE receives a signal, is
equal to 20 MHz and the bandwidth of Carrier 2, through which the
UE receives a signal, is equal to 400 MHz will be assumed. In this
case, if the UE equally splits the buffer and equally allocates the
split buffer to Carrier 1 and Carrier 2, even if there is a large
difference in bandwidth between Carrier 1 and Carrier 2, the signal
shall be received at the same transmission rate. However, due to a
lack of frequency resource in Carrier 1, it may be difficult to
receive the signal as much as the required transmission rate in
Carrier 1.
In this specification, the terms mini-slot, slot, and subframe are
used as terms for expressing transmission units. In the present
invention, each term can be interchangeably replaced with other
terms. For example, the term enhanced Mobile BroadBand
(eMBB)-specific subframe that is used in the exemplary embodiment,
which will be described below, may be replaced with the term
eMBB-specific slot. The content of the present invention may also
be applied to other exemplary embodiments applying the same concept
as the exemplary embodiment of this specification.
The carrier (band) of this specification may correspond to
different carriers (or different bands) within the NR, and the
carrier (band) of this specification may also correspond to
different carries within the NR and LTE. More specifically, the
present invention may be applied to CA or DC within the NR, or the
present invention may also be applied to CA or DC between the NR
and LTE.
In the present invention, each of the proposed techniques may be
separately or collectively applied. For example, Proposed Technique
1 may be applied along with subsidiary embodiments of Proposed
Technique 1. As another example, Proposed Technique 1 may be
applied along with Proposed Technique 4.
A maximum size of a transmittable TB may vary as described below
based on a subcarrier width and a bandwidth. Firstly, it will be
given that, in case a subcarrier width of 15 kHz is applied to 20
kHz and scheduling is configured in subframe units having 14 OFDM
symbols, a maximum size of a transmittable TB is equal to
TB.sub.max. In this case, the TB.sub.max according to the
subcarrier width and the bandwidth varies as described below.
In case both the bandwidth and the subcarrier width are increased
linearly, the TB.sub.max is constantly maintained. For example, if
the bandwidth is increased to 80 MHz whereas the subcarrier width
is increased to 60 MHz, since the number of subcarriers within the
bandwidth is constantly maintained, the size of the TB.sub.max is
constant.
If the bandwidth is constant, and if only the subcarrier width
increases, since the number of subcarriers within the carrier
decreases, the size of the TB.sub.max decreases. For example,
although the bandwidth is constantly 20 MHz, if the subcarrier
width is increased to 60 MHz, the size of the TB.sub.max is
decreased to 1/4. As another example, although the bandwidth is
increased to 40 MHz, if the subcarrier width is increased to 60
MHz, the size of the TB.sub.max is decreased to 1/2.
If the bandwidth increases whereas the carrier width is constant,
since the number of subcarriers within the bandwidth increases, the
size of the TB.sub.max is increased. According to the same
principle, if the increased size of the bandwidth is greater than
the increased size of the subcarrier width, the TB.sub.max is
increased. For example, if the bandwidth increases to 80 MHz
whereas the subcarrier width is constantly 15 MHz, the size of the
TB.sub.max is increased to 4 times. As another example, if the
bandwidth increases to 160 MHz and the subcarrier width increases
to 60 kHz, the size of the TB.sub.max is increased to 2 times.
In a 5G NR communication system, cases such as the above-described
exemplary embodiment may occur. For example, in order to satisfy
the low latency condition of Ultra-Reliable and Low Latency
Communications (URLLC) in a carrier of 6 GHz or below, a subcarrier
width of 60 kHz may be applied. As another example, in order to
ensure coverage in a carrier of 6 GHz or below, a subcarrier width
of 15 kHz or 30 kHz having a long CP length may be applied. In this
case, an FFT size that is used when performing OFDM symbol
modulation may be increased to 4096. Additionally, in a same
carrier, the subcarrier width of Partial Band 1 may be set to 15
kHz, and the subcarrier width of Partial Band 2 may be set to 60
kHz.
In a 5G communication system, scheduling may be performed in
subframe units as well as slot or mini-slot units having shorter
time durations than subframe. The change in the TB.sub.max size
according to the scheduling time unit is as described below.
Generally, a subframe is configured of 14 OFDM symbols, and a slot
is configured of 7 OFDM symbols. Since the number of symbols in a
slot is 1/2, in case scheduling is performed in slot units, the
size of the TB.sub.max becomes 1/2.
The mini-slot has a smaller number of OFDM symbols than the slot.
For example, in case the number of OFDM symbols within a mini-slot
is equal to 1, the size of the TB.sub.max becomes 1/4.
According to the soft buffer size being allocated to each carrier
or partial band, the size of the TB.sub.max that can be used in
each carrier or partial band may be limited, or a modulation scheme
and coding rate (e.g., MCS level) being applied when transmitting a
TB may be limited. More specifically, limited buffer rate matching
(LBRM) may be applied in the base station based on the soft buffer
size per partial band of the UE. If the LBRM is applied, coding
gain occurs. And, as the soft buffer size becomes smaller, the
decrease in coding gain increases.
Based on the above-described observation results, the present
invention proposes a method of efficiently splitting, by a UE being
connected to multiple partial bands or carriers, the soft buffer to
each carrier and partial band. In the following exemplary
embodiment, it will be given that the size of a soft buffer
belonging to the UE is equal to N.sub.soft, and that the UE is
connected to N.sub.C number of carriers, and that a partial band of
an n.sub.c.sup.th carrier corresponds to N.sub.p. Herein, each of
N.sub.soft, N.sub.C, and N.sub.p is an integer greater than 1. In a
specific carrier, if N.sub.p=1, this indicates that the carrier is
not split (or divided) to partial bands.
The details proposed in this specification are as described
below.
<Proposed Technique 1>
The UE divides (or splits) the soft buffer in proportion to the
number of subcarriers in each partial band. As a first example,
N.sub.soft may be allocated in proportion to the number of
subcarriers SC.sub.n of each partial band. Herein, N=1, 2, . . . ,
N.sub.C*N.sub.p. As a second example, N.sub.soft may be split and
allocated in proportion to the number of resource blocks RB.sub.n
of each partial band. Herein, N=1, 2, . . . , N.sub.C*N.sub.p. In
another example, it is given that the bandwidth of an n.sup.th
partial band is equal to BW.sub.n and that the subcarrier width is
equal to SCS.sub.n. Herein, N=1, 2, . . . , N.sub.C*N.sub.p.
N.sub.soft may be allocated in proportion to BW.sub.n/SCS.sub.n. As
a third example, when the bandwidth of an n.sup.th partial band is
equal to BW.sub.n, and when an RF bandwidth that can be received,
by the UE, from the corresponding partial band is RFBW.sub.n,
N.sub.soft may be allocated in proportion to RFBW.sub.n/SCS.sub.n.
Herein, N=1, 2, . . . , N.sub.C*N.sub.p.
In order to perform the above-described operations, the UE
explicitly or implicitly receives a number of subcarriers in each
partial band from the base station. For this, when the base station
transmits a higher layer signal to the UE, a value of the signal is
generated based on a number of subcarriers in a carrier or partial
band being connected to each UE or based on a value that is
proportional to the number of subcarriers. Since the base station
knows the carrier and partial band being connected to the UE and
their characteristics, TB size selection, code block segmentation,
LBRM, and so on, are performed based on the soft buffer size of
each carrier or partial band of the UE.
As described in the observation results presented above, when the
subcarrier width is constant, if the bandwidth increases, the
TB.sub.max also increases, and, when the bandwidth is constant, if
the subcarrier width increases, the TB.sub.max decreases.
Therefore, it will be preferable to split (or divide) the soft
buffer in proportion to the bandwidth and in inverse-proportion to
the subcarrier band. Additionally, a sum (or combination) of the
partial bands may be greater than the bandwidth of a carrier
through which partial bands are transmitted. For example, when a
carrier has 2 partial bands each having a bandwidth of BW.sub.1 and
BW.sub.2, and when the partial bands are processed with FDM, the
sum of the partial band bandwidth may be greater than the bandwidth
of the carrier BW.sub.c. More specifically,
BW.sub.c.ltoreq.BW.sub.1+BW.sub.2. As another example, when the
carrier has 2 partial bands and the number of subcarriers in each
partial band is respectively equal to SC.sub.1 and SC.sub.2, and
when the number of subcarriers of the corresponding carrier is
equal to SC.sub.c, SC.sub.c.ltoreq.SC.sub.1+SC.sub.2. This is
because the band of the partial bands may overlap one another.
Typically, Partial Band 1 may correspond to a partial band
dedicated to eMBB services using only part of the entire band, and
Partial Band 2 may correspond to a partial band dedicated to URLLC,
which may use the entire band. Therefore, in Proposed Technique 1,
instead of allocating the soft buffer to each carrier and then
allocating the soft buffer to the partial bands within each
carrier, the soft buffer is allocated based on the partial
bands.
The bandwidth that is used in the third example of Proposed
Technique 1 may correspond to a bandwidth including a guard band or
may correspond to a bandwidth not including a guard band.
Generally, since communication is not performed in a guard band, it
will be preferable to set up BW.sub.n as a bandwidth excluding a
guard band. In a first example, since each subcarrier or a number
of subcarriers in each partial band is used, the guard band is
already excluded. More specifically, a buffer size being allocated
to an n.sup.th carrier or partial band may be as described
below.
In a first example, a buffer size being allocated to an n.sup.th
carrier or partial band may be indicated as shown below.
.alpha..times..times..times..times..times..times. ##EQU00001##
In a second example, a buffer size being allocated to an n.sup.th
carrier or partial band may be indicated as shown below.
.alpha..times..times..times..times..times..times. ##EQU00002##
In a third example, a buffer size being allocated to an n.sup.th
carrier or partial band may be indicated as shown below.
.alpha..times..times..times..times..times..times. ##EQU00003##
Herein, .alpha. represents a value being determined by another
factor, and N=1, 2, . . . , N.sub.C+N.sub.p.
As another example, the UE may split (or divide) the soft buffer in
proportion to an aggregation (or combination) of multiple partial
bands. For example, when it is assumed that Partial Bands 1, 2, 3,
4, and 5 are included in a specific carrier being is connected to
the UE, a new Partial Band #A may be configured by aggregating (or
combining) Partial Bands 1 and 2, and another Partial Band #B may
be configured by aggregating 3, 4, and 5. Accordingly, the UE may
distribute the soft buffer in proportion to the size of Partial
Band #A and Partial Band #B.
<Proposed Technique 1.1>
Along with Proposed Technique 1 or separately, the size of the soft
buffer being distributed to each partial band by the UE may vary in
proportion to the number of OFDM symbols for performing scheduling.
Herein, it will be given that the number of OFDM symbols being
included in a unit performing scheduling in an n.sup.th carrier or
partial band is equal to OFSym.sub.n. The size of the soft buffer
may be distributed to each carrier or partial band in proportion to
OFSym.sub.n.
In order to perform the above-described operation, the base station
explicitly or implicitly notifies the scheduling unit to the UE via
higher layer signal. Additionally, the base station performs TB
size selection, code block segmentation, LBRM, and so on, based on
the soft buffer size of each carrier or partial band of the UE.
As in the above-described observation results, if the subcarrier
width and bandwidth are constant, if the number of OFDM symbols of
the scheduling unit varies, the TB.sub.max also varies. The soft
buffer size of a case where Proposed Technique 1.1 is applied may
be distributed as described below.
In a first example of the Proposed Technique 1, a soft buffer size
may be indicated as shown below.
.alpha..times..times..times..times..times..times..times..times.
##EQU00004##
In a second example of the Proposed Technique 1, a soft buffer size
may be indicated as shown below.
.alpha..times..times..times..times..times..times..times..times.
##EQU00005##
In a third example of the Proposed Technique 1, a soft buffer size
may be indicated as shown below.
.alpha..times..times..times..times..times..times..times..times.
##EQU00006##
Herein, .alpha. represents a value being determined by another
factor, and N=1, 2, . . . , N.sub.C+N.sub.p.
<Proposed Technique 1.2>
Along with Proposed Technique 1 and/or Proposed Technique 1.1 or
separately, the soft buffer is allocated in proportion to a number
of Hybrid Automatic Repeat request (HARQ) processes being applied
to each partial band. For example, when the number of HARQ
processes of Partial Band 1 is equal to 4 and the number of HARQ
processes of Partial Band 2 is equal to 8, and when other
parameters are the same, Partial Band 2 is allocated with a soft
buffer having a size that is 2 times larger than that of Partial
Band 1.
In order to perform the above-described operations, the base
station explicitly or implicitly notifies the number of HARQ
processes to the UE via UE-specific signal. Additionally, the base
station performs TB size selection, code block segmentation, LBRM,
and so on, based on the soft buffer size of each carrier or partial
band of the UE.
In NR, in case each partial band has a different numerology and
supports different services, each partial band may have a different
number of HARQ processes. If the number of processes increases, the
required soft buffer size increases accordingly. Therefore, the
soft buffer size may be configured (or set) in proportion to the
number of HARQ processes.
<Proposed Technique 1.3>
The proposed technique applies soft buffer splitting while
considering a maximum modulation scheme of each carrier or partial
band. For example, in case the maximum modulation scheme of Carrier
1 is 1024QAM and the maximum modulation scheme of Carrier 2 is
256QAM, a maximum of 10-bit information may be transmitted from 1
RE in Carrier 1, and a maximum of 8-bit information may be
transmitted from 1 RE in Carrier 2. Therefore, under the same
condition, among the entire soft buffer, 10/18 of the buffer is
allocated to Carrier 1, and 8/18 of the buffer is allocated to
Carrier 2.
<Proposed Technique 1.4>
Along with Proposed Technique 1 and/or Proposed Technique 1.1
and/or Proposed Technique 1.2 or separately, the soft buffer size
may be varied based on a minimum coding rate or maximum coding rate
or a reference coding rate being applied to each carrier or partial
band. For example, it will be given that a minimum coding rate that
can be used in the n.sup.th partial band is equal to r.sub.n. At
this point, the soft buffer size may be distributed to each partial
band in inverse-proportion to r.sub.n. As another example, in
addition to the minimum coding rate, r.sub.n may also correspond to
a maximum coding rate or a reference coding rate.
In order to perform the above-described operations, the base
station explicitly or implicitly notifies the minimum coding rate
or maximum coding rate or reference coding rate to the UE via
UE-specific signal. As an example of the implicit notification,
when there are 2 base graphs of LDPC, and when the minimum coding
rates of each base graph are different from one another, the base
station may implicitly notify the minimum coding rate by indicating
the base graph that is used by the base station for channel
encoding. Additionally, the base station performs TB size
selection, code block segmentation, LBRM, and so on, based on the
soft buffer size of each carrier or partial band of the UE.
In the NR, a minimum coding rate or a maximum coding rate or a
reference coding rate being applied to a physical layer may vary
based on the service that is provided to the UE. For example,
although up to a 1/12 coding rate is supported in URLLC, only up to
a 1/3 coding rate is supported in eMBB. In this case, even if the
same TB is transmitted, the URLLC requires a buffer size that is 4
times larger than that of the eMBB. Therefore, the soft buffer size
may vary in inverse-proportion to the minimum coding rate being
applied to each carrier or partial band. As another example,
although a maximum coding rate of 3/4 coding rate is supported in
URLLC, only up to an 8/9 coding rate is supported in eMBB. Since a
case of gaining the maximum coding rate corresponds to a case of
applying the highest coding rate, the soft buffer may be
distributed based on the maximum coding rate of each carrier or
partial band. As another example, the coding rate that is most
frequently used in URLLC may be 1/2, and the coding rate that is
most frequently used in eMBB may be 2/3. In this case, the soft
buffer size may be distributed based on the most frequently used
coding rate.
<Proposed Technique 2>
The UE divides (or splits) the soft buffer in proportion to the
number of subcarriers in each subcarrier being connected to the UE
(or UE-specific carrier). Thereafter, the UE splits the soft buffer
per partial band within the soft buffer. Herein, the process of
splitting (or dividing) the soft buffer per partial band may be
semi-statically or dynamically processed. Herein, a time gap
between a change in the soft buffer size of each carrier may differ
from a time gap between a change in the soft buffer size of each
partial band. As an example of the above-described technique,
N.sub.soft may be allocated per partial band in proportion to the
number of subcarriers of each carrier SC.sub.n, wherein n=1, 2, . .
. , N.sub.C. Thereafter, the allocated N.sub.soft is allocated per
partial band. As another example, it will be given that the
bandwidth of an n.sup.th carrier is equal to BW.sub.n, wherein n=1,
2, N.sub.C and that the subcarrier width is equal to SCS.sub.n.
Herein, N.sub.soft may be allocated per carrier in proportion to
BW.sub.n/SCS.sub.n, and, then, the allocated N.sub.soft is
allocated per partial band. As another example, when the bandwidth
of an n.sup.th carrier (UE-specific carrier) is equal to BW.sub.n,
and when an RF bandwidth that can be received, by the UE, from the
corresponding carrier (UE-specific carrier) is RFBW.sub.n,
N.sub.soft may be allocated in proportion to
RFBW.sub.n/SCS.sub.n.
In order to perform the above-described operations, the UE
explicitly or implicitly receives a number of subcarriers in each
carrier from the base station. For this, when the base station
transmits a higher layer signal to the UE, a value of the signal is
generated based on a number of subcarriers in a carrier or partial
band being connected to each UE or based on a value that is
proportional to the number of subcarriers. Since the base station
knows the carrier and partial band being connected to the UE and
their characteristics, TB size selection, code block segmentation,
LBRM, and so on, are performed based on the soft buffer size of
each carrier or partial band of the UE.
Although the bandwidth and number of subcarriers in each carrier
are values that hardly change (or vary), the bandwidth and number
of subcarriers in each partial band may semi-statically or
dynamically vary (or change). Unlike the Proposed Technique 1, this
technique corresponds to a method of firstly allocating the soft
buffer per carrier and then allocating the soft buffer per partial
band when needed. Therefore, as compared to Proposed Technique 1,
this method is more adequate (or appropriate) for being applied to
a case where the soft buffer is semi-statically allocated per
carrier and where the soft buffer is semi-statically allocated
according to a shorter cycle period or dynamically allocated per
partial band. However, in case the partial band of each carrier is
allocated with a specific overlapping subcarrier, it will be
disadvantageous in that the soft buffer is not allocated in
proportion to the number of subcarriers in each partial band.
<Proposed Technique 2.1>
In addition to the Proposed Technique 2 for splitting each carrier
to the soft buffer, allocation may be performed based on the number
of OFDM symbols used for performing scheduling of each carrier
and/or the number of HARQ processes and/or the maximum modulation
scheme and/or a minimum/maximum/reference coding rate of a mother
code.
Although Proposed Technique 1.1 to Proposed Technique 1.4 are
described based on a case where the soft buffer is allocated per
carrier, the proposed techniques may also be applied to a case
where the soft buffer is allocated per carrier. For example, in
case of splitting the soft buffer by using the number of
subcarriers in each carrier, the number of OFDM symbols for
performing scheduling, and the number of HARQ processes, the soft
buffer size per carrier is as described below.
.alpha..times..times..times..times..times..times..times..times..times..ti-
mes. ##EQU00007##
Herein, in SC.sub.n, n=1, 2, N.sub.C, and M.sub.n represents a
number of HARQ processes. When performing the above-described
operations, although one carrier has 2 partial bands, in case the
number of HARQ processes and the scheduling units of each partial
band are different from one another, a method for calculating such
values is needed. In case such values are not applied, when
splitting soft buffer per carrier, a method of allocating the soft
buffer only based on the number of subcarriers, and, afterwards,
allocating the soft buffer per partial band based on the number of
OFDM symbols, the number of HARQ processes, and so on, may be used.
Alternatively, for the above-described reasons, Proposed Technique
1 may be applied. Alternatively, a specific rule may be selected
and applied. The corresponding method is as described below.
<Proposed Technique 2.1.1>
A method for determining a number of HARQ processes of a carrier
having multiple partial bands and a number of OFDM symbols for
performing scheduling includes the following options.
Opt 1) A partial band being allocated with the largest band within
the carrier is defined as a main partial band, and the number of
OFDM symbols for performing scheduling of the corresponding band
and the number of HARQ processes are used in the carrier. In this
case, the number of carriers may be calculated based on the carrier
band.
Opt 2) A partial band having the greatest
SC.sub.nOFSym.sub.nM.sub.n value within the carrier is defined as a
main partial band, and the number of OFDM symbols for performing
scheduling of the corresponding band and the number of HARQ
processes are used in the carrier. In this case, the number of
carriers may be calculated based on the carrier band.
Opt 3) The partial bands within the carrier are multiplied by a
weighting factor.
Opt 4) In case partial bands are split to eMBB and URLLC, when
performing scheduling of eMBB, the number of OFDM symbols and the
number of HARQ processes are applied.
Opt 5) Soft buffer splitting is performed in partial band units as
described in Proposed Technique 1.
<Proposed Technique 2.2>
When splitting the soft buffer, which is split to each carrier, to
each partial band, the soft buffer may be allocated in proportion
to a number of subcarriers in each partial band. As an example of
the above-described technique, Buffer.sub.n may be allocated per
carrier in proportion to the number of subcarriers of each partial
band SC.sub.m, wherein m=1, 2, . . . , N.sub.P. Thereafter, the
allocated N.sub.soft is allocated per partial band. As another
example, Buffer.sub.n may be allocated per carrier in proportion to
a number of resource blocks of each carrier RB.sub.m, wherein m=1,
2, . . . , N.sub.P. Thereafter, Buffer.sub.n is allocated per
partial band in proportion to the number of RBs in each partial
band. As another example, it will be given that the bandwidth of an
n.sup.th carrier is equal to, wherein n=1, 2, . . . , N.sub.P, and
that the subcarrier width is equal to SCS.sub.n. Herein, N.sub.soft
is allocated per carrier in proportion to BW.sub.n/SCS.sub.n, and,
then, N.sub.soft is allocated in proportion to the partial
band.
In order to perform the above-described operations, the UE
explicitly or implicitly receives a number of subcarriers in each
partial band from the base station. For this, when the base station
transmits a higher layer signal to the UE, a value of the signal is
generated based on a number of subcarriers in a carrier or partial
band being connected to each UE or based on a value that is
proportional to the number of subcarriers. Since the base station
knows the carrier and partial band being connected to the UE and
their characteristics, TB size selection, code block segmentation,
LBRM, and so on, are performed based on the soft buffer size of
each carrier or partial band of the UE.
Proposed Technique 1.1 to Proposed Technique 1.4 may also be
applied to the above-described operation as described below.
<Proposed Technique 2.2.1>
In addition to the Proposed Technique 2 for splitting each partial
band to the soft buffer, allocation may be performed based on the
number of OFDM symbols used for performing scheduling of each
carrier and/or the number of HARQ processes and/or the maximum
modulation scheme and/or a minimum/maximum/reference coding rate of
a mother code.
For example, in case of splitting the soft buffer by using the
number of subcarriers in each carrier, the number of OFDM symbols
for performing scheduling, and the number of HARQ processes, the
soft buffer size per partial band is as described below.
.alpha..times..times..times..times..times..times..times..times.
##EQU00008##
Herein, in SC.sub.n, n=1, 2, . . . , N.sub.C, and M.sub.n
represents a number of HARQ processes. When performing the
above-described operations, the method of splitting the soft buffer
per carrier will not be limited to only one specific method.
<Proposed Technique 2.3>
Thereafter, in case a priority of a specific partial band within a
specific carrier is high, the base station indicates a soft buffer
size that shall be reserved for the corresponding partial band to
the UE via higher layer signaling. For example, it will be assumed
that a specific carrier is divided (or split) to 2 partial bands,
and that Partial Band 1 corresponds to a partial band dedicated to
URLLC and Partial Band 2 corresponds to a partial band dedicated to
eMBB. Since URLLC requires high reliability, it will be preferable
not to apply limited rate matching. Therefore, the UE reserves a
soft buffer size that is required for the URLLC by using the
TB.sub.max of a URLLC-dedicated partial band, a number of HARQ
processes, a number of layers, and so on, and uses the remaining
soft buffer size for eMBB. Alternatively, the base station may
notify the soft buffer size that is to be reserved for URLLC to the
UE via higher layer signal. Additionally, the base station performs
TB size selection, code block segmentation, LBRM, and so on, based
on the soft buffer size of each carrier or partial band of the
UE.
In the above-described exemplary embodiment, it is assumed that a
soft buffer size being allocated to a specific carrier is equal to
N.sub.soft,n and that the corresponding carrier is divided (or
split) to Partial Bands 1 and 2. In this case, since Partial Band 1
has a higher priority than Partial Band 2, the UE may reserve a
buffer size corresponding to N.sub.partial, 1 for Partial Band 1
and may perform limited rate matching for Partial Band 2 in the
remaining buffer size corresponding to N.sub.soft,n-N.sub.partial,
1.
<Proposed Technique 3>
The soft buffer size is distributed based on a maximum number of
CBs that can be transmitted from a single TB in each partial band
being connected to the UE. For example, the maximum number of CBs
may be calculated by dividing TB.sub.max by a maximum length of the
CB (e.g. 8192) so as to obtain the CB.sub.n of each carrier or
partial band, and, then, N.sub.soft may be divided and allocated in
proportion to the calculated value. Herein, n=1, 2, . . . ,
N.sub.C*N.sub.p. And, the base station performs TB size selection,
code block segmentation, LBRM, and so on, based on the soft buffer
size of each carrier or partial band of the UE.
When the TB is divided to multiple CBs, the TB is generally divided
based on the CB having the greatest length. This is because the
channel coding performance (or capability) is generally greater as
the length of a codeblock becomes longer. Therefore, if the soft
buffer is divided (or split) based on the maximum number of CBs
that can be transmitted by each UE when the TB size is equal to
TB.sub.max, the soft buffer may be distributed to each carrier and
partial band based on TB.sub.max.
In case the soft buffer is divided (or split) based on the CB, a
problem may occur if the maximum CB sizes of each carrier or
partial band are different from one another. For example, since the
packet size of URLLC is expected to be smaller than that of eMBB,
the maximum CB of URLLC may be smaller than the maximum CB of eMBB.
In this case, even though the TBs have the same size, the maximum
number of CB included in the corresponding TBs may be different
from one another. More specifically, since the URLLC may have a
larger number of CBs than the eMBB, the URLLC may be allocated with
a larger soft buffer size.
<Proposed Technique 4>
A case where the UE is simultaneously connected to LTE and NR will
be assumed. In this case, the UE may calculate the soft buffer as
described below, and the base station may perform LBRM according to
the following rule.
Opt 1) In case the bandwidth of the NR is equal to or greater than
20 MHz, the bandwidth of the NR may be divided by 20 MHz so as to
deduce a number of virtual cells, and, then, a number of configured
serving cells is calculated based on the deduced number of virtual
cells. For example, in case the UE is connected to an NR carrier
and LTE carrier of 100 MHz, the number of configured serving cells
of the UE is equal to 6, and 1/6 of the soft buffer is allocated
for the LTE.
Opt 2) The UE randomly configures an LTE UE category based on the
soft buffer size, and, then, notifies the configured LTE UE
category to the base station.
Opt 3) The UE may view an LTE carrier to be the same as an NR
carrier and may perform soft buffer splitting accordingly. An NR
base station notifies a soft buffer size being allocated to LTE by
the UE to an LTE base station. Alternatively, the UE directly
notifies the corresponding soft buffer size to the LTE base
station. Herein, the NR base station may correspond to a master
base station (or primary cell) or a secondary base station (or
secondary cell).
Opt 4) The master base station determines an allocation ratio of a
UE soft buffer and notifies the determined allocation ratio to a
secondary base station configured to the UE. The master base
station may transfer (or deliver) the corresponding ratio
information to the UE via UE-specific signal, and the UE performs
LBRM by allocating the soft buffer according to the determined
ratio. Herein, the master base station may correspond to an LTE
base station or an NR base station.
In LTE, it is assumed that the bandwidth of a carrier being
connected to the UE is equal to 20 MHz, and soft buffer splitting
is performed accordingly. However, in the NR, the UE may be
allocated with a band of 20 MHz or higher in a single carrier.
Therefore, a soft buffer splitting method considering a case where
the UE is connected to both NR and LTE is needed.
Opt 1 corresponds to a method of permuting one NR cell having a
large bandwidth to multiple LTE cells. For example, in case one NR
carrier has a band of 150 MHz, the corresponding carrier may be
permuted to 7 or 8 LTE serving cells, and, then, soft buffer
splitting may be performed accordingly. More specifically, the
buffer is allocated as much as N.sub.soft/8 or N.sub.soft/9 in LTE.
In NR, the buffer is allocated as much as 7N.sub.soft/8 or
8N.sub.soft/9, and the exemplary embodiment of the above-described
Proposed Techniques 1.about.3 may be applied to the corresponding
soft buffer, thereby being capable of allocating the soft
buffer.
Opt 2 corresponds to a method of randomly selecting, by a UE, an
LTE UE category based on its soft buffer size and NR bandwidth and
notifying the values to an LTE base station and an NR base station.
The NR base station may acquire a soft buffer size that is to be
used in NR, by the UE, by using the UE category that is reported to
the LTE by the UE. More specifically, if the buffer size that is to
be used in LTE by the UE is equal to L.sub.soft, the buffer size
that is to be used in NR by the UE is equal to
N'.sub.soft=N.sub.soft-L.sub.soft. The UE may allocate the soft
buffer based on N'.sub.soft by applying the exemplary embodiments
of Proposed Techniques 1.about.3.
Opt 3 corresponds to a method of allocating the soft buffer, by the
UE, by applying the same rule to the LTE and the NR and, then,
notifying the corresponding value. In Opt 3, in order to avoid
configuring an interface between an additional UE and the base
station, the NR base station may notify the soft buffer size to the
LTE base station. For this, the NR base station shall be aware of
the number of LTE base stations being connected to the UE (or the
number of LTE base stations being configured to the UE).
Opt 4 corresponds to a method of determining, by a master base
station (or cell), an allocation ratio of a UE soft buffer and,
then, notifying the allocation ratio of the soft buffer to
secondary base stations (or cells). Herein, the master base station
may correspond to an LTE base station or an NR base station.
<Proposed Technique 5>
A carrier or partial band being configured to the UE (or
UE-specific carrier or partial band) may be activated/deactivated.
In this case, the soft buffer being allocated to each UE may be
allocated as described below.
Opt 1) The soft buffer may be allocated to each carrier or partial
band based on a carrier or partial band being configured to the
UE.
Opt 2) The soft buffer may be allocated to each carrier or partial
band based on a carrier or partial band being activated to the UE.
In this case, even if the number of carriers or partial bands being
configured to the UE is constant, the soft buffer size being
allocated, by the UE, to each carrier or partial band may vary (or
change) based on the activation/deactivation of the carrier or
partial band, and the LBRM is then performed accordingly.
The proposed technique relates to a method for configuring a
reference standard, by the UE, for allocating the soft buffer, and,
herein, the above-described Proposed Techniques 1 to 4 and the
subsidiary clauses may also be used when allocating the soft
buffer.
Opt 1 is appropriate for a case where the UE is configured to
different base stations and where each base station
activates/deactivates the carrier or partial band for a specific
UE. This is because, in case a base station fails to acknowledge
the activation/deactivation of a neighboring (or adjacent) base
station, the corresponding base station may determine a wrong soft
buffer size that is allocated and transmit a signal
accordingly.
Opt 2 is appropriate for a case where the UE is configured to one
base station and where the carrier or partial band within the base
station is activated/deactivated and for a case where the UE is
configured to multiple base stations and activation/deactivation
information is exchanged between the multiple base stations. Opt 2
is advantageous in that the soft buffer may be more efficiently
used as compared to Opt 1. However, this is because the base
stations being configured to the UE shall be capable of exchanging
activation/deactivation information. Alternatively, this method may
also be applied to a case where the UE transmits signaling that
notifies, to all base stations being configured to the UE, the
activated carriers or partial bands among the carriers or partial
bands being configured to the UE. The signal may be transferred (or
delivered) to the base stations via L2/L3 signal or RRC signal.
As an exemplary soft buffer splitting equation of this
specification, this equation may be applied to an equation and
table adopting the same principle.
FIG. 6 is a diagram showing a procedure for transmitting a
transport block according to an exemplary embodiment of this
specification.
This exemplary embodiment proposes a method of efficiently
splitting (or dividing), by a UE being connected to multiple
partial bands or carriers, a soft buffer for carriers and partial
bands. The UE may be allocated with at least one carrier, and the
specific carrier may include at least one partial band. If the
number of partial bands is equal to 1, it may be understood that
the specific carrier is not split (or divided) to partial
bands.
In step S610, the UE receives information on the number of
subcarriers in a partial band being included in the allocated
carrier from the base station. The number of subcarriers in the
partial band may be explicitly or implicitly received from the base
station via higher layer signaling.
In step S620, the UE may distribute a soft buffer included in the
UE in proportion to the number of subcarriers of the partial band.
For example, if the partial band includes a first partial band and
a second partial band, the soft buffer may be distributed based on
the number of subcarriers in the first partial band and the number
of subcarriers in the second partial band.
In step S630, the UE determines a transport block size per partial
band based on the distributed soft buffer size. The transport block
size may correspond to a maximum transport block size that can be
transmitted from the partial band.
In step S640, the UE transmits a transport block to the base
station within the determined transport block size.
If the bandwidth of the partial band is constant whereas a gap
between the subcarriers increases, the number of subcarriers of the
partial band may be decreased. Accordingly, the soft buffer size
being distributed to the partial band is decreased, and the
transport block size being transmitted from the partial band may be
decreased.
If the bandwidth of the partial band is increased whereas a gap
between the subcarriers is constant, the number of subcarriers of
the partial band may be increased. Accordingly, the soft buffer
size being distributed to the partial band is increased, and the
transport block size being transmitted from the partial band may be
increased.
In case the partial band includes a first partial band and a second
partial band, a sum (or combination) of a bandwidth of the first
partial band and a bandwidth of the second partial band may be
equal to or larger than the bandwidth of the carrier. In this case,
the first partial band and the second partial band may be processed
with Frequency Division Multiplexing (FDM).
In case the partial band includes a first partial band and a second
partial band, a sum (or combination) of a number of subcarriers in
the first partial band and a number of subcarriers in the second
partial band may be equal to or larger than the number of
subcarriers in the carrier. In this case, the first partial band
and the second partial band may overlap one another. For example,
the first partial band may support enhanced Mobile BroadBand (eMBB)
services, and the second partial band may support Ultra-Reliable
and Low Latency Communications (URLLC) services. More specifically,
the first partial band may correspond to a partial band dedicated
to eMBB services using only part of the entire band, and the second
partial band may correspond to a partial band dedicated to URLLC,
which may use the entire band. The entire band may correspond to
the entire carrier band being allocated to the UE.
Additionally, the soft buffer belonging to the UE may be
distributed in proportion to a number of Orthogonal Frequency
Division Multiplexing (OFDM) symbols being scheduled in the partial
band. More specifically, if a gap between the subcarriers and the
bandwidth are constant, the soft buffer size or maximum transport
block size may vary (or change) in proportion to the number of
symbols, which corresponds to units for performing scheduling of
the partial band. The number of OFDM symbols being scheduled in the
partial band may be received via higher layer signal.
Additionally, the soft buffer belonging to the UE may be
distributed in proportion to a number of Hybrid Automatic Repeat
request (HARQ) processes of the partial band. The number of HARQ
processes may be received via UE-specific signal.
Additionally, the soft buffer belonging to the UE may be
distributed in proportion to a maximum number of information bits
being supported by a maximum modulation scheme of the partial band.
For example, in case the maximum modulation scheme of the first
partial band is 1024QAM and the maximum modulation scheme of second
partial band is 256QAM, a maximum of 10-bit information may be
transmitted from 1 RE in the first partial band, and a maximum of
8-bit information may be transmitted from 1 RE in the second
partial band. Therefore, under the same condition, among the entire
soft buffer, 10/18 of the buffer is allocated to the first partial
band, and 8/18 of the buffer is allocated to the second partial
band.
Additionally, the soft buffer belonging to the UE may be
distributed in inverse proportion to a minimum coding rate being
applied to the partial band. The minimum coding rate may be
received via UE-specific signal. Furthermore, the UE may distribute
the soft buffer based on the minimum coding rate as well as the
maximum coding rate or the reference coding rate.
In case multiple carrier are allocated from the base station, the
soft buffer belonging to the UE may be distributed in proportion to
the number of subcarriers of the carrier before the soft buffer is
distributed in proportion to the number of subcarriers of the
partial band. More specifically, after the UE distributes its soft
buffer to each carrier, the UE may re-distribute the soft buffer
per partial band.
The UE may be simultaneously connected to a first communication
system and a second communication system. The first communication
system may correspond to a 5G NR system, and the second
communication system may correspond to an LTE system. Based on a
number of cells being configured to the first communication system
and a number of cells being configured to the second communication
system, the soft buffer belonging to the UE may be distributed to
each of the first communication system and the second communication
system.
At this point, the number of cells being configured to the first
communication system may be acquired based on a bandwidth that is
supported by the first communication system. And, the number of
cells being configured to the second communication system may be
acquired based on a bandwidth that is supported by the second
communication system. Since the 5G NR system supports a wider
bandwidth than the LTE system, the number of cells being configured
to the first communication system may be greater than the number of
cells being configured to the second communication system.
FIG. 7 is a block diagram showing a wireless device to which an
exemplary embodiment of this specification can be applied.
Referring to FIG. 7, as a device (or apparatus) that can implement
the above-described exemplary embodiment, the wireless device may
operate as a base station or user equipment (UE). Additionally, the
wireless device may correspond to a receiving device, or the
wireless device may correspond to a transmitting device
transmitting a signal to the receiving device.
As shown in the drawing, the wireless device of FIG. 7 includes a
processor (710), a memory (720), and a transceiver (730). Each of
the processor (710), memory (720), and transceiver (730) shown in
FIG. 7 may be implemented as a separate chip, or at least two or
more blocks/functions may be implemented through a single chip.
The transceiver (730) is a device including a transmitter and a
receiver, and when a specific operation is performed, the
transceiver (730) may perform the operations of any one of the
transmitter and the receiver, or the transceiver may perform the
operations of both the transmitter and the receiver. The
transceiver (730) may include one or more antennas transmitting
and/or receiving radio signals. Additionally, the transceiver (730)
may include an amplifier for amplifying a reception signal and/or a
transmission signal and a band-pass filter for performing
transmission over a specific frequency band.
The processor (710) may implement functions, processes, and/or
methods proposed in this specification. For example, the processor
(710) may perform operations according to the above0described
exemplary embodiment of this specification. More specifically, the
processor (710) may perform the operations disclosed in the
exemplary embodiment shown in FIG. 1 to FIG. 6.
The processor (710) may include an application-specific integrated
circuit (ASIC), a separate chipset, a logic circuit, a data
processing unit, and/or a converter inter-converting baseband
signals and radio signals. The memory (720) may include a read-only
memory (ROM), a random access memory (RAM), a flash memory, a
memory card, a storage medium, and/or other equivalent storage
devices.
FIG. 8 is a block diagram showing an example of a device being
included in a processor. For simplicity in the description,
although an example of FIG. 8 is described based on a block for a
transmission signal, it will be apparent that a reception signal
may be processed by using the corresponding block.
A data processing unit (810) shown in FIG. 8 generates transmission
data (control data and/or user data) corresponding to a
transmission signal. An output of the data processing unit (810)
may be inputted to an encoder (820). The encoder (820) may perform
coding by using binary convolutional code (BCC) or low-density
parity-check (LDPC) coding schemes. At least one encoder (820) may
be included herein, and the number of encoders (820) may be
determined based on diverse information (e.g., number of data
streams).
An output of the encoder (820) may be inputted to an interleaver
(830). The interleaver (830) may perform operations of distributing
consecutive bit signals within a radio resource (e.g., time and/or
frequency) in order to prevent any burst error, which is caused by
fading, and so on. At least one interleaver (830) may be included
herein, and the number of interleavers (830) may be determined
based on diverse information (e.g., number of spatial streams).
An output of the interleaver (830) may be inputted to a
constellation mapper (840). The constellation mapper (840) may
perform constellation mapping, such as biphase shift keying (BPSK),
Quadrature Phase Shift Keying (QPSK), n-quadrature amplitude
modulation (QAM), and so on.
An output of the constellation mapper (840) may be inputted to a
spatial stream encoder (850). The spatial stream encoder (850)
performs data processing in order to transmit a transmission signal
via at least one spatial stream. For example, the spatial stream
encoder (850) may perform at least one of space-time block coding
(STBC), Cyclic shift diversity (CSD) insertion, and spatial mapping
on the transmission signal.
An output of the spatial stream encoder (850) may be inputted to an
IDFT (860) block. The IDFT (860) block may perform inverse discrete
Fourier transform (IDFT) or inverse Fast Fourier transform
(IFFT).
An output of the IDFT (860) block is inputted to a Guard Interval
(GI) inserter (870), and an output of the GI inserter (870) is
inputted to the transceiver (730) of FIG. 7.
* * * * *